Non-Destructive Inspection of Surface Integrity in Milled Turbine Blades of Inconel 738LC

2013 ◽  
Vol 486 ◽  
pp. 9-15 ◽  
Author(s):  
Kamil Kolařík ◽  
Zdenek Pala ◽  
Libor Beranek ◽  
Jiří Čapek ◽  
Zdenek Vyskocil ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Surface Integrity ◽  
Turbine Blades ◽  
Mutual Effect ◽  
Work Piece ◽  
Machined Surface ◽  
Grain Sizes ◽  
Cutter Orientation ◽  
Inconel 738Lc ◽  
Non Destructive

Nickel super-alloys are widely used in aerospace as material for turbine blades. Unfortunately, their machining is difficult since mechanical hardening and, consequently, extreme tool wear occur. Casting can no longer meet the requirements for precision, hence, the castings are being ground or milled. In this contribution, a quality check of the milled surface by several surface integrity parameters is proposed with respect to the surface structural inhomogeneities caused by mutual effect of plastic deformations and thermal fields during the cutting process. Castings from Inconel 738LC were milled with cutting conditions chosen by Design-Of-Experiments method and the resulting surfaces were assessed by non-destructive X-ray diffraction methods in several areas corresponding to various cutter orientation and work-piece angle. Surface integrity was described by macroscopic residual stresses, microstrains, grain sizes and phase composition. Mostly, favourable compressive surface residual stresses were observed in the cutting direction, grain sizes were distinctively smaller when the tool axis was perpendicular to the machined surface.

Surface Integrity of Die Material in High Speed Hard Machining, Part 1: Micrographical Analysis

1999 ◽  
Vol 122 (4) ◽  
pp. 620-631 ◽  
Author(s):  
T. I. El-Wardany ◽  
H. A. Kishawy ◽  
M. A. Elbestawi
Keyword(s):  
Tool Wear ◽  
Residual Stresses ◽  
Tool Steel ◽  
Surface Integrity ◽  
High Speed ◽  
Cutting Conditions ◽  
Metallographic Analysis ◽  
Tool Geometry ◽  
Machined Surface ◽  
Geometrical Defects

The effects of cutting conditions and tool wear on chip morphology and surface integrity during high speed machining of D2 tool steel (60–62 Hrc) are investigated experimentally and analytically in this paper. Polycrystalline Cubic Boron Nitride (PCBN) tools are used in this investigation. The chips and the subsurface of the workpiece are examined using optical and scanning electron microscopy. Microhardness measurements are performed on the surface and subsurface of the workpiece. The X-ray diffraction technique is used to measure the residual stresses induced in the machined surface. The paper is divided into two parts. Part 1 presents the results obtained from the micrographical analysis of the chips and the surfaces produced. Part 2 deals with microhardness and residual stresses of the machined surface. The micrographical analysis of the chips produced shows that different mechanisms of chip formation exist depending on the magnitude of the cutting pressure and tool wear. Saw toothed chips are produced during the machining of D2 tool steel if the cutting pressure exceeds approximately 4000 MPa. The metallographic analysis of the surface produced illustrates the damaged surface region that contains geometrical defects and changes in the subsurface metallurgical structure. The types of surface damage are dependent on the cutting conditions, tool geometry and the magnitude of the wear lands. [S1087-1357(00)00104-0]

The influence of turning parameters on surface integrity of nickel alloy 625

2016 ◽  
Vol 232 (10) ◽  
pp. 1837-1847 ◽  
Author(s):  
Daniel Loureiro ◽  
Anselmo E Diniz ◽  
Alexandre B Farina ◽  
Sérgio Delijaicov
Keyword(s):  
Residual Stresses ◽  
Surface Integrity ◽  
Cold Work ◽  
Cutting Speed ◽  
Tool Geometry ◽  
Machined Surface ◽  
Alloy 625 ◽  
Industrial Sectors ◽  
Coated Carbide ◽  
Compressive Residual Stresses

Nickel-based alloys are used in industrial sectors where high mechanical strength and corrosion resistance are required at high temperatures. However, these alloys have low machinability as a consequence of inherent properties. Some of these properties such as high cold work hardening rate and low heat conductivity may cause damages to the machined surface. Among the nickel-based alloys, one that has good properties for oil exploration is alloy 625. As the components made of this alloy are frequently used in very rough environments, this study sought to evaluate the influence of tool geometry, cutting conditions (feed and cutting speed) and tool condition (fresh or worn) on the surface integrity of turned alloy 625 parts in order to discover turning practices for this alloy that result in minimal damage to the workpiece surface. A secondary aim was to evaluate how these input variables affected the life of the coated carbide tools used in the turning experiments with this alloy. The main conclusions are that (a) the surfaces produced with a fresh tool with positive geometry had compressive residual stresses, while those produced with negative tool geometry had tensile residual stresses and (b) when a worn tool was used all the surfaces produced had compressive residual stresses.

Analysis of Reversible Fine Machining Sequence Effect on Surface Integrity

2006 ◽  
Vol 315-316 ◽  
pp. 391-395
Author(s):  
Wen Ge Wu ◽  
Si Qin Pang ◽  
Zhan Qiang Liu
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Machining Process ◽  
Processing Route ◽  
Machining Accuracy ◽  
Machining Efficiency ◽  
Micro Hardness ◽  
Rough Machining ◽  
Machined Surface

Reversible cutting method is a new research thesis proposed to shorten processing route, decrease tool number and handling time, increase machining efficiency. The aim of the presented work was to analysis the effects of reversible fine machining sequence on surface integrity in machined layer. Nonlinear hardening during reverse loading and the change of the Bauschinger effect factor with plastic strain were properly taken into account. In experiments, the residual stresses have been measured using the X-ray diffraction technique (at the surface of the workpiece and in depth). Moreover, micro-hardness and surface roughness of machined surface are presented. Experimental data for the range of cutting parameters tested showed that the reversible fine machining produce the tensile residual stresses at the surface, which are critical in the performance of the machined components. The experimental results of micro-hardness of reversible fine machining technique are smaller than that of general fine machining show that decreased plastic deformation of the surface layer and work-hardening. Surface roughness of machined surface with reversible finishing is discussed. Research results indicted that it can be adopted such planning which rough machining during advance stroke and fine machining or semi-finishing during return stroke in machining process. In this way, it has such advantages that increase machining efficiency and machining accuracy, decrease bending deformation.

Experimental Investigation into Surface Integrity Finished by Abrasive Jet with Grinding Wheel as Restraint

2007 ◽  
Vol 359-360 ◽  
pp. 244-248 ◽  
Author(s):  
Chang He Li ◽  
Shi Chao Xiu ◽  
Guang Qi Cai
Keyword(s):  
Residual Stresses ◽  
Surface Integrity ◽  
High Surface ◽  
Surface Hardness ◽  
Ground Surface ◽  
Grinding Wheel ◽  
Workpiece Material ◽  
Machined Surface ◽  
X Ray ◽  
Finished Surface

The surface integrity finished by abrasive jet with grinding wheel as restraint was experimentally investigated. Experiments were performed with plane grinder M7120 equiped with abrasive jet finishing device and harded workpiece material 45 steel which was ground with the surface roughness values of Ra=0.6μm.The machined surface morphology was studied using Scanning Electron Microscope (SEM) and microscope and microcosmic geometry parameters were measured with TALYSURF5 instrument. The surface hardness for ground and finished surface was measured with HVS-1000 instrument and the phase structure was analyzed by X-ray energy dispersive spectram and residual stresses were measured by PW3208 X-ray diffraction. The Results show that longitudinal geometry parameter values were diminished and ripple was obviously improved comparing with ground surface. Furthermore, the finished surface has condensible residual stresses and high surface hardness comparability compared to grinding machining surface. As a result, life and precision consistency of finished workpiece were improved.

Influence of Milling on Surface Integrity of Ti-6Al-4V

2013 ◽  
Vol 698 ◽  
pp. 127-136 ◽  
Author(s):  
Kamel Moussaoui ◽  
Michel Mousseigne ◽  
Johanna Senatore ◽  
Pierre Lagarrigue ◽  
Yves Caumel
Keyword(s):  
Residual Stresses ◽  
Surface Integrity ◽  
Cutting Speed ◽  
Orange Peel ◽  
Influential Factor ◽  
Nose Radius ◽  
Machined Surface ◽  
Naked Eye ◽  
Deformed Layer ◽  
Softened Zone

The present article addresses the influence of milling on the surface integrity of Ti-6Al-4V. Observation of the machined surface from a macroscopic perspective (naked eye) has highlighted anorange peelphenomenon. Under the machined surface no plastically deformed layer or lengthening of the grains were observed. As far as microhardness is concerned, a slightly softened zone was noted under the machined surface. Diffusion of vanadium from phase β to phase α also occurred but without resulting change to the microstructure. Measurement of microhardness and residual stresses showed that the finishing pass predominated over the roughing pass in terms of its influence on surface integrity. The response surface methodology was used in order to highlight those parameters influencing surface integrity. Its application and processing showed that the most influential factor is the nose radius for roughness and the cutting speed for residual stresses.

scholarly journals The prediction of the turned machining induced residual stresses in Ti6Al4V: A Critical Surface Integrity Descriptor

2021 ◽  
Vol 347 ◽  
pp. 00037
Author(s):  
Gary Styger ◽  
Rudolph F Laubscher
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Cutting Speed ◽  
Element Model ◽  
Rake Angle ◽  
Critical Surface ◽  
Machining Parameters ◽  
Machined Surface ◽  
Wide Range

The surface integrity of a turned machined surface is an essential indicator of the fatigue and corrosion performance of a component. A critical descriptor of this property is the residual stress, both on the surface and subsurface of a part. However, experimental determination of vital surface integrity parameters such as surface roughness, hardness, affected microstructure, and residual stresses is costly, time consuming, and involves the destruction of the part. Therefore, prediction of these parameters, such as residual stress versus depth, would be of great value and could aid in the correct machining parameters (cutting speed, feed rate, edge tool radius, rake angle, coolant) for the desired part performance. A study was initiated to determine the influence of a worn tool and multiple cuts on a wide range of cutting speeds on residual stresses induced by machining an outside-turned bar of Ti6Al4V titanium alloy. Thus, a project was initiated to develop a non-linear finite element model to predict the residual stresses thus developed due to the machining manufacturing process.

Investigation of the Impact of Cutting Parameters on Surface Integrity in the End Milling of Inconel 625

2019 ◽  
Vol 969 ◽  
pp. 762-767 ◽  
Author(s):  
Ramesh Rajguru ◽  
Hari Vasudevan
Keyword(s):  
Residual Stresses ◽  
Surface Integrity ◽  
Cutting Parameters ◽  
Rake Angle ◽  
Inconel 625 ◽  
Micro Hardness ◽  
Machined Surface ◽  
Radial Rake Angle ◽  
Radial Depth ◽  
The Impact

Nickel based super alloys, such as Inconel 625 is amongst the most difficult to machine, due to its low thermal conductivity and high strength at higher temperature. Although, they are used in aerospace exhaust systems and other applications, the strain hardening that results during the machining operation, which adversely affects surface integrity of machined surface of such materials especially in extensive applications, is a cause for concern. In this context, this study was carried out, involving the milling operation, using solid carbide tools coated with TiAlSiN, under specifically developed conditions for dry machining of the difficult to cut materials. The cutting parameters were 4 in number, namely radial rake angle, feed per tooth, cutting speed and radial depth of cut and the response parameters included surface integrity characteristics, such as residual stresses, surface roughness and micro-hardness. Based on the experimental analyses, it was found that the micro-hardness of machined surface was higher. Micro hardness of sub surface decreases with the depth (50,100,150,250μm) due to a reduction in the work hardening of the Inconel 625, underneath the surface layer. The residual stresses were analyzed using main effect plot, and it was seen that the residual stresses were significantly influenced by the radial rake angle, followed by feed per tooth.

The Attempt of New Approach to Evaluate Surface Integrity

2016 ◽  
Vol 368 ◽  
pp. 15-19
Author(s):  
Jiří Malec ◽  
Filip Červinka ◽  
Dominik Blažíček ◽  
Janne Suoknuuti
Keyword(s):  
Residual Stresses ◽  
Surface Integrity ◽  
Noise Analysis ◽  
Surface Damage ◽  
Noise Signal ◽  
Barkhausen Noise ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
New Approach

Machined surface of hard steel parts like gears, bearings, camshafts etc. is full of local imperfections which are commonly described in terms of surface integrity. This surface integrity is usually quantified with the level of residual stresses or amplitude of Barkhausen noise signal for instance. The contribution introduces parameter called Sum of Effective Residual Stresses (SERS) to describe the level of surface damage after grinding. Experimental data obtained by X-Ray Diffraction (XRD) and Barkhausen Noise Analysis (BNA) methods of ground gears are shown. The way to use SERS approach for experimental determination of penetration depth of Barkhausen signal in steels is proposed, too.

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